The prior art in this context is reflected in the printed publications U.S. Pat. No. 5,207,656, U.S. Pat. No. 5,549,651, and U.S. Pat. No. 4,475,548, with U.S. Pat. No. 5,207,656 being the most closely related. It reveals a medical instrument valve having a foamed sealing region, for example in the form of a catheter introducer. The housing incorporates a valve for receiving and sealing an elongated member, which penetrates the valve. The valve itself incorporates an elastomeric partition member. This partition member is presented to facilitate the penetration and sealing of an elongated member into the body. It comprises a closed-cell foamed material, inside which a fluid is enclosed as a lubricant, to support the penetration by an elongated member by reducing the friction. It is a shortcoming of this embodiment that the outer surface of the foamed material, i.e., the side in which an elongated member is to be inserted into the valve, is designed flat. This can make it difficult to precisely position the elongated member for its penetration of the foamed material member. This means that at times a passage has to be found through the foamed material member. This is not pleasant, however, for the patient or for the medical personnel.
U.S. Pat. No. 5,549,651 describes a medical valve and fluid transfer method. The context is an intravenous tubing system that is provided with a valve. The valve has a piston and a seal affixed to its front for the tubing system. Only the seal is manufactured of an elastic material. It is positioned in a guide means disposed perpendicular to the main line. This guide means has, in the proximal region, in the longitudinal direction, viewed in the direction of the main line, two opposed projections that the seal squeezes together in these two regions when the seal is guided into this direction. The seal has a continuous slit along the length, which, during the insertion process, forms an oval opening through pressure onto the two laterally disposed pressure points. A fluid may now be passed through this opening. However, no provision is made for a supply with a medical instrument, as in the previously mentioned patent documents.
U.S. Pat. No. 4,475,548 describes a valve body. The foamed material of the valve body is preferably a surgical rubber material that has been foamed. According to its description it does not form any closed cells. For the patent document, this has the advantage that an exchange of fluid is possible from one cell to the next. However, at the same time this also means that a gas-tight implementation is not possible. An absolute seal between a space located behind a body cavity and the environment can thus not be created. It is thus not possible to perform surgery under sealed conditions.
Trocars are known both made of plastic as disposable articles, as well as made of metal as re-usable instruments, and essentially consist of a trocar sleeve, which is inserted into the abdominal wall, and a sealing arrangement in the form of a valve, which is disposed in a so-called valve cage in the form of a housing that is wider than the trocar sleeve and located at the access end of the trocar sleeve. The trocar sleeve and valve cage are generally connected to one another in a detachable manner to allow for easy cleaning.
Disposed inside the valve cage is a valve arrangement, which allows the inserted surgical instrument to pass through and provides a seal for the patient's abdominal cavity from the atmosphere when the instrument is removed, e.g., when instruments are changed. A rubber seal or rubber cap that has been adapted to the instrument diameter accomplishes the sealing of the abdominal cavity, after the instrument has been inserted.
Valve arrangements of this type require relatively large and heavy valve cages, which cause an undesirable “top-heaviness” of the trocar. Also, the conventional valves are difficult to clean and incomplete cleaning entails the risk of an infection to the patient.